1. Field of the Invention
The present invention relates to method and system for acquiring delivery position data on a predetermined delivery position by a carrying apparatus.
2. Description of the Related Art
A substrate processing system for processing substrates has a plurality of processing units for processing substrates by different processes, respectively. The substrate processing system is provided with a substrate carrying apparatus that carries a substrate from one processing unit to another.
The substrate carrying apparatus needs to carry a substrate accurately to a desired position in a transfer unit included in each processing unit. Otherwise, it is possible that the substrate is processed irregularly, the substrate falls off the transfer unit and/or undesired particles adhere to the substrate.
Practically, the hand of the substrate carrying apparatus is unable to carry the substrate accurately to a desired position, the substrate cannot be correctly positioned and the substrate cannot be normally carried due to positional errors in the substrate carrying apparatus and the substrate processing system. To position the substrate accurately, a first conventional position teaching method teaches a delivery position to the substrate carrying apparatus by the manual operation of the substrate carrying apparatus by the user. However, it is practically impossible for the user to teach the delivery position to the substrate carrying apparatus by manually operating the substrate carrying apparatus. Moreover, skillful manual operation of the substrate carrying apparatus is necessary to achieve accurate teaching of the delivery position to the substrate carrying apparatus in a short time.
A second conventional position teaching method, such as a method disclosed in JP-A 11-186360, uses an object to be detected which is placed at a desired delivery position, and a detector held by the substrate carrying apparatus. The second conventional position teaching method teaches the delivery position to the substrate carrying apparatus on the basis of a value provided by an encoder at the detection of the object by the detector.
Referring to FIG. 23 showing a flow chart of a conventional delivery position teaching procedure using a detector, the delivery position teaching procedure is started in step f0 after the substrate carrying apparatus and the substrate processing system have been initialized for a delivery position teaching operation. In step f1, the operator places an object to be detected at a delivery position to which a substrate is to be carried. In step f2, the operator mounts a detector for detecting the object to be detected on the hand of the substrate carrying apparatus.
In step f3, the operator instructs the substrate carrying apparatus to move the hand to an estimated delivery position through a manual operation or on the basis of data for CAD (computer-aided design). In step f4, the operator gives a delivery position data acquisition instruction to the substrate carrying apparatus to make the substrate carrying apparatus acquire delivery position data, and then the substrate carrying apparatus acquires delivery position data automatically. More specifically, after the hand has been moved to an estimated delivery position, the hand is moved to search a position of the hand where the object is detected. The substrate carrying apparatus calculates the delivery position on the basis of a value provided by an encoder upon the detection of the object by the detector and then notifies the operator of the completion of a delivery position data acquiring operation.
Then, in step f5, the operator removes the detector from the hand and removes the object from the delivery position. The delivery position teaching procedure is ended in step f6.
A third conventional position teaching method attaches a CCD camera (charge-coupled device camera) to the hand of a carrying apparatus and determines a position to be taught to the carrying apparatus by processing images formed by the CCD camera. A system for carrying out the third conventional position teaching method is of a large scale and expensive.
The second conventional position teaching method moves the hand to the estimated delivery position where the detector is able to detect the object to be detected in step f3. The manual hand moving operation must move the hand to the estimated delivery position so that the hand may not collide with obstacles. Or, the accurate coincidence of the current condition with the CAD data is essential. The hand cannot be easily moved to the estimated delivery position when a space in which the substrate carrying apparatus operates is narrow. Acquisition of delivery position data on a delivery position for other kinds of carrying apparatuses has the same problems as those in the acquisition of delivery position data for the substrate carrying apparatus.